System and Method for Production of Ultra-Pure Hydrogen from Biomass

ABSTRACT

The disclosure provides a system and method for synthesizing ultra-pure hydrogen from biomass waste. The present invention comprises a gasifier, an oils and tars filter, a steam generator, a water gas shift reactor (“WGS”), a heat-exchange two-phase water separator, a scrubber, a hydrogen separator, and fluid conduits in fluid communication with the various system components, which together convert hydrocarbon-based biomass, e.g., woodchips, into ultra-pure hydrogen gas. Fluid conduits connect the gasifier and the steam generator, separately, to the WGS, the WGS to the two-phase separator, the two-phase separator to the scrubber, and the scrubber to the hydrogen separator, which further comprises an outlet port through which hydrogen gas may flow free of carbon monoxide. The hydrogen may flow to a device that utilizes hydrogen to generate energy, such as a hydrogen fuel cell or to an internal combustion engine.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/155,800, filed May 1, 2015 and entitled PRODUCTION OF ULTRA-PUREHYDROGEN FROM BIOMASS WASTE TO ENERGIZE PROTON EXCHANGE MEMBRANE (PEM)AND PRODUCE USEFUL COMBINED HEAT AND ELECTRIC POWER (CHEP).

GOVERNMENT RIGHTS STATEMENT

The invention disclosed herein was made at least in part with funding bythe U.S. Government, specifically the United States Department of Energyunder grant number DE-EE0003228. Therefore, the U.S. Government hascertain rights in this invention.

FIELD

The present disclosure relates to a hydrogen purification method andsystem and, more particularly, to a method and system for hydrogenpurification from biomass fuel.

BACKGROUND

Recent concern over the state of the environment, the dangers of highlevels of greenhouse gas emissions and global warming has sparked arecognition of the need to develop clean renewable energy sources.Biomass gasification of abundant organic materials such as wood chips,forest residue and farm waste is a leading source of clean renewableenergy that, in addition to other constituents, can result in asynthesis gas that can contain up to 19% hydrogen (H2) and 20% carbonmonoxide (CO).

By chemically processing such constituent materials, useful gases may berecovered and used to produce various forms of energy, includingelectrical and mechanical energy. This electrical energy may be used topower homes, industrial buildings, and farm and industrial machinerylocated far away from a power grid.

Hydrogen fuel cells are a promising technology for use as electricalpower sources. With only water as by-product and no greenhouse gasesemissions, hydrogen fuel cells provide considerable environmentalbenefits. Fuel cells receive hydrogen as an input and return electricalenergy that may be used in numerous applications. Hydrogen for fuelcells can be produced in several ways, such as through fossil fuelreformation, the steam-iron process, thermochemical water splitting, andwater electrolysis.

Fossil fuel reforming accounts for approximately 95% today's hydrogenproduction, and is a chemical process in which steam reacts at a hightemperature with a fossil fuel inside of a “reformer” to producehydrogen and carbon monoxide. Reforming typically occurs in the presenceof a metal-based catalyst and at high temperatures of 700 to 1100° C.This process can be applied to a large range of hydrocarbon feedstocks,including propane, gasoline, autogas, methanol, diesel fuel, andethanol. However, this process is limited to the availability of fossilfuels, which will increase in cost and decrease in availability in thefuture.

The steam-iron process is one of the oldest known methods for producinghydrogen in which coal is gasified to a lean reducing gas made up ofhydrogen and carbon monoxide. This gas then reacts with iron oxide,typically such as magnetite (Fe₃O₄), to produce wustite (FeO) and/oriron metal (Fe). Then, the wũstite and/or iron metal is re-oxidized withsteam to form magnetite and H2 gas.

The steam-iron process takes place at temperatures ranging from 600 to900° C., but may occur at lower temperatures when the reaction takesplace in the presence of catalysts such as transition metal or potassiumhydroxide. Further, the steam-iron process may also occur at lowertemperatures when the reactive surface area of the iron-bearingwater-reducing material is increased through processes such as grinding.However, the availability and price of coal, as well as use of a fossilfuel, remain a large drawback.

In thermochemical water splitting, the intense heat required to splitwater into hydrogen and oxygen is typically derived from concentratedsunlight or recycled waste heat from a nuclear reactor. Consequently,this process involves near-zero greenhouse gas emissions, but remainsunder development to identify reactor designs, systems, and materialsthat will be cost-efficient and durable. Therefore, a commerciallyviable thermochemical reactor is as of yet unavailable.

Similarly, conventional water electrolysis involves the splitting ofwater into hydrogen and oxygen via an electric current, but is veryexpensive and consumes high amounts of energy in comparison to fossilfuel-based processes. As an improvement to conventional waterelectrolysis, to reduce the amount of electrical energy required tofacilitate water splitting, a method of supplying natural gas to theelectrolyzer has been proposed, as reflected in U.S. Pat. No. 6,051,125.

However, this method requires fossil fuel consumption, as well asmonitoring of electrodes that may become contaminated with carbondeposited by reaction of natural gas with oxygen. An alternative methodof electrolyzing high-temperature steam at a high-temperature of 800° C.or higher. In this method, high levels of thermal energy are substitutedfor the high levels of electrical energy typically required toelectrolyze water, thereby lowering reducing the electrical powerrequired for water electrolysis. But, the required thermal energy isoften derived from fossil fuels.

For hydrogen to be used in hydrogen fuel cells, a high degree of purityis critical as even trace impurities present in the H2 can poison theanode, membrane, and cathode of the fuel cell, resulting in reduced andinefficient performance. In order to efficiently produce ultracleanhydrogen that may be effectively used to generate electricity, carbonmonoxide levels must be kept to an absolute minimum, particularly atless than 10 parts per million, to ensure that a hydrogen fuel cellremains efficient and functional.

Therefore, as hydrogen produced by the available known methods typicallyeither includes unacceptable levels of impurities or, to produce H2 ofsufficient purity or requires excessively high levels of energy input,there remains a need for a method of producing high purity hydrogen atlow cost without greenhouse gases emissions.

SUMMARY

The following summary of the invention is intended to provide a basicunderstanding of some aspects of the invention. This summary is notmeant to identify all key or critical elements of the invention or todelineate the entire scope of the invention. Its sole purpose is topresent some concepts of the invention in a simplified form as a preludeto the more detailed description that is subsequently presented.

The present invention comprises a gasifier, a steam generator, a watergas shift reactor (“WGS”), a heat-exchange two-phase water separator, ascrubber, a hydrogen separator, and fluid conduits, in fluidcommunication with the various system components, which together converthydrocarbon-based biomass, e.g., woodchips, into ultra-pure hydrogengas. Fluid conduits connect the gasifier and the steam generator,separately, to the WGS, the WGS to the two-phase separator, thetwo-phase separator to the scrubber, and the scrubber to the hydrogenseparator, which further comprises an outlet port through which hydrogengas may flow free of carbon monoxide. The hydrogen may flow to a devicethat utilizes hydrogen to generate energy, such as a hydrogen fuel cellor to an internal combustion engine.

The gasification chamber breaks down biomass fuel into basic chemicalelements through a series of chemical reactions to form a synthetic gas,or syngas, which flows out of the gasifier and into the fluid conduitconnecting the gasifier to the WGS. The steam generator supplies steamto the syngas flow to increase the water vapor content of the syngasbefore entering the WGS. The steam and syngas mix and pass into the WGSwhere they react in the presence of a catalyst to form additionalhydrogen gas mixed with other gases such as carbon dioxide, carbonmonoxide, and nitrogen. The gas mixture passes through the scrubberwhere carbon monoxide is extracted. Then, the scrubbed gas passes intothe carbon monoxide separator and the hydrogen separator where hydrogenis isolated from the remainder of the scrubbed gas mixture, providing astream of ultra-pure hydrogen separated from the other byproduct gases.

In practice, biomass conversion begins when a user deposits biomass intothe gasifier, creating syngas flow and mixes with the steam from thesteam generator. Syngas conversion continues as biomass is fed into thegasifier. Simultaneously, syngas flows through fluid conduits where itis mixed with steam, and into the water gas shift, bubbling scrubber,and hydrogen separator. Operation of the system may terminate uponcompletion of biomass conversion into syngas and syngas purificationinto hydrogen gas and byproduct gases.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive features will be described withreference to the following figures, wherein like reference numeralsrefer to like parts throughout the various figures. The figures belowwere not intended to be drawn to any precise scale with respect to size,angular relationship, or relative position.

FIG. 1 is a schematic depicting a diagram of the individual componentsof the present invention

FIG. 2 is a schematic depicting an exemplary down draft gasifier.

FIG. 3 is a schematic depicting an exemplary steam generator.

FIG. 4 is a photograph depicting a sample configuration of a steamgenerator designed to maximize heat absorption and fuel sourceefficiency.

FIG. 5 is a photograph of a steam generator operating to create steamand water vapor.

FIG. 6 is a schematic depicting the structure and composition of anexemplary water gas shift reactor.

FIG. 7 is a schematic depicting the general structure of an exemplarybubbling scrubber.

FIG. 8 is a photograph depicting an exemplary configuration of thebubbling scrubber using a standard laboratory beaker.

FIG. 9 is a schematic depicting an exemplary configuration of theelectrochemical hydrogen separator, implemented to achieve purificationof the hydrogen gas.

FIG. 10 is a schematic depicting the structure of an exemplary hydrogenfuel cell.

DETAILED DESCRIPTION

These, and other, aspects and objects of the present invention will bebetter appreciated and understood when considered in conjunction withthe following description and the accompanying drawings. It should beunderstood, however, that the following description, while indicatingpreferred embodiments of the present invention and numerous specificdetails thereof, is given by way of illustration and not of limitation.

Many changes and modifications may be made within the scope of thepresent invention without departing from the spirit thereof and theinvention includes all such modifications, such as, but not limited toimplementing other types of gasifiers not of the down draft design,implementing various designs of bubbling scrubber devices or steamgenerators, or using various types of catalysts in the water gas shiftreaction.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with an embodiment is included inat least one embodiment of claimed subject matter. Thus, appearances ofphrases such as “in one embodiment” or “an embodiment” in various placesthroughout this specification are not necessarily all referring to thesame embodiment. Furthermore, particular features, structures, orcharacteristics may be combined in one or more embodiments.

The use of biomass as a source of energy dates back to the use of woodto create fires by early human species. Today, wood remains the largestsource of biomass energy, and includes, but is not limited to, deadtrees, branches, tree stumps, yard clippings, farm waste like cornhusks, forest debris and wood chips. Industrial biomass is often grownfrom various types of small and medium plants such as tall grass andtree species, wherein any potential crops from the plant are harvestedand the remainder of the plant is sold as biomass.

In the renewable energy market, the conversion of waste to energy is anattractive source of energy that has used systems such as incineration,with recent innovation resulting in systems such as gasification,pyrolysis, anaerobic digestion, and plasma gasification. On anindustrial scale across the globe, few large-scale gasificationapplications are in place, with little to no commercial gasificationbeing conducted in the United States. Current technologies harnessenergy from a wide range of waste products, such as fish and chickenfarms, most garbage, plastics and manure, to create syngas.

The present invention comprises a novel system for converting biomassinto ultra-pure hydrogen, including at least a gasifier, an oils andtars filter, a steam generator, a water gas shift reactor, aheat-exchange two-phase water separator, a scrubbing mechanism, anelectrochemical separator, and fluid conduits, two phase separatorsestablishing fluid communication with the various system components. Thepresent invention converts biomass, e.g., woodchips, into a syntheticgas that is cleaned and purified through a series of thermal, chemicaland electrical reactions and processes, resulting in ultra-pure hydrogengas that may be used for a wide range of applications, e.g., in ahydrogen fuel cell.

In one embodiment, the hydrogen gas may be fed into a hydrogen fuelcell. After passing through the elements just described, the hydrogen isused by a hydrogen fuel cell to generate electricity. In anotherembodiment, hydrogen gas exiting the electrochemical separator of thepresent invention can be directed into an internal combustion engine,where it is ignited to generate mechanical energy that drives acomponent of the engine, e.g., a piston, rotor, or turbine blade.

Syngas produced from a gasifier undergoes several chemical reactionsthroughout this process, and a scrubber is incorporated into the presentinvention in an effort to remove as much carbon monoxide from the syngasas possible before hydrogen is separated from the syngas. As previouslydiscussed in the Background section above, carbon monoxide needs to beremoved from the hydrogen gas that is supplied to a conventional fuelcell because the carbon monoxide can contaminate and poison the anodes,membranes and cathodes, degrading performance and ultimately causingfailure of the fuel cell.

FIG. 1 depicts the present invention, comprising a gasifier 100, an oilsand tars filtration system 101, a steam generator 118, a water gas shiftreactor (“WGS”) 104, a heat-exchange two-phase water separator 105, ascrubber 106, a hydrogen separator 108, and fluid conduits 102, 119,117, 116, 115, 114, 112, and 110. Fluid conduits 102, 119, 117, 116, 115and 114 establish and provide a network of fluid communication betweenthe elements just described, while fluid conduits 112 and 110 functionto carry away hydrogen gas and other gases, respectively, from thehydrogen separator 108. In preferred embodiments, fluid conduit 112 maysupply ultra-pure hydrogen gas to a hydrogen fuel cell, to an internalcombustion engine or to a hydrogen gas storage system and receptacle.

As shown in FIG. 1, the WGS 104, the heat-exchange two-phase separator105, the scrubber 106 and the hydrogen separator 108 are all connecteddownstream from the gasifier 100, wherein syngas leaving the gasifiertravels through fluid conduit 102 to the WGS 104. Further, the steamgenerator 118 is connected to fluid conduit 102 downstream of thegasifier 100 by fluid conduit 119, and provides water vapor that ismixed into the syngas before it enters the WGS 104.

The WGS catalyst converts the water vapor and carbon monoxide intoadditional hydrogen gas and carbon dioxide, and a modified syngasproduct leaves the WGS 104 through fluid conduit 116 and passes throughthe heat-exchange two-phase water separator 105, through fluid conduit115 and into the scrubber 106. Scrubbed syngas, i.e., having most of thecarbon monoxide removed, then travels out of the scrubber 106, throughfluid conduit 114 and into the hydrogen separator 108. Hydrogen gasexits the hydrogen separator 108 through fluid conduit 112 while otherresulting byproduct gases exit the hydrogen separator 108 through fluidconduit 110.

The gasifier 100 functions to convert biomass into syngas, and thissyngas product primarily includes molecules of carbon dioxide (CO2),carbon monoxide (CO), hydrogen (H2), and nitrogen (N2) in a gaseousstate. The steam generator 118 functions to create steam from liquidwater (H2O, i.e., “dihydrogen monoxide”), which may be mixed with thesyngas output from the gasifier 100.

The WGS 104 functions to convert carbon monoxide and water into carbondioxide and water, thereby facilitating removal of carbon monoxide fromthe syngas. Because the WGS reaction is typically slow at lowtemperatures, the WGS 104 contains a catalyst that facilitates thechemical reaction between the carbon monoxide and water vapor. Theresulting gas mixture of the modified syngas product includes primarilymolecules of nitrogen, carbon dioxide, additional hydrogen and watervapor, with only relatively much smaller amounts of carbon monoxideremaining.

Most of the water vapor exiting the WGS 104 will next be cooled andcondensed by the heat-exchange two-phase water separator 105, with thecondensed liquid water then being recycled back to the steam generator.The gaseous fraction of the fluid processed by the heat-exchangetwo-phase water separator 105 is then sent through fluid conduit 115 tothe scrubber 106.

The scrubber 106 functions to remove most of the remaining carbonmonoxide from the modified syngas product following processing by theWGS 104. Finally, the hydrogen separator 108 isolates hydrogen gas fromother the other modified syngas product components and outputs hydrogengas separate from the byproduct gases, which now include primarilycarbon dioxide and nitrogen.

In operation, biomass is fed into the gasifier 100 where it chemicallyreacts in the presence of heat to form syngas and ash. Hot syngas exitsthe gasifier 100 through the syngas outlet port 128, which connects tofluid conduit 102. Simultaneously, water vapor from the steam generator118 travels through fluid conduit 119 into fluid conduit 102 where itcomes into fluid contact with the syngas and mixes to form a watervapor-enriched syngas.

Aside from syngas, the gasifier 100 may produce tar that is not utilizedby the present invention and requires filtration from the syngas beforethe syngas enters subsequent elements of the present invention. In orderto achieve maximum efficiency of the present invention, tar must befiltered from the syngas before it enters the WGS 104, and is preferablyfiltered from the syngas immediately after exiting the gasifier 100 byan oils and tars filtration system 101. Among other mechanisms capableof implementing the oils and tars filtration system 101, and in apreferred embodiment oils and tars are filtered by an activated carbonsystem.

Water vapor exiting the steam generator 118 passes into fluid conduit119 which is in fluid communication with fluid conduit 102 such thatsyngas from the gasifier 100 comes into fluid contact with the hot watervapor in fluid conduit 102. A pump may be implemented to move watervapor from the steam generator 118 through fluid conduit 119 and intofluid conduit 119, which pump may comprise any type of pump,specifically including, but not limited to, an aspirator pump, venturipump, or other pump enabling a venturi or venture-type effect. However,it should be understood that the claimed subject matter is not intendedto be limited in scope to employing a pump to move hot water vaporthrough fluid conduit 119 to fluid conduit 102, and may not include anypump whatsoever, or may achieve water vapor movement via other means.

The mixture of syngas and water vapor travels through fluid conduit 102to the WGS 104, where a catalyst facilitated chemical reaction convertscarbon monoxide and water vapor into carbon dioxide and hydrogen gasaccording to the equation CO+H2O=CO2+H2, essentially transferring theoxygen atom from a molecule of water vapor (H2O) and adding it to acarbon monoxide (CO) molecule to make carbon dioxide (CO2). The watervapor molecules (H2O) having been stripped of their oxygen atoms,transform into hydrogen gas molecules (H2).

This modified syngas product (hydrogen enriched syngas) exits the WGS104, passes through fluid conduit 116 and flows through theheat-exchange two-phase water separator 105, where water vapor iscondensed into liquid water and removed, into fluid conduit 115 and intothe scrubber 106, which functions to remove most of the carbon monoxideremaining in the modified syngas product output by the WGS 104.

Scrubbed gas flows out of the scrubber 106 through fluid conduit 114into the hydrogen separator 108 where the hydrogen gas is chemicallyseparated from the remainder of the gas mixture. Hydrogen gas leaves thehydrogen separator 108 through fluid conduit 112 and the remainder ofbyproduct gases in the gas mixture exit the hydrogen separator 108through fluid conduit 110.

The gasifier 100 serves as the source of syngas synthesis in the presentinvention, converting biomass into syngas. In preferred embodiments, aco-current fixed bed “down draft” style gasifier is implemented.However, the gasifier design may also be implemented as, but is notlimited to, a counter-current fixed bed “up draft” style gasifier,inclined rotary style gasifier, fluidized bed, entrained bed, or plasmagasifier.

The down draft gasifier presents the ideal configuration of gasifierdesign to achieve maximum hydrogen gas production from input biomass,and by implementing a down draft gasifier the present invention attemptsto maximize hydrogen production efficiency. FIG. 2 depicts the generalstructure of a down draft gasifier, in which a series of thermochemicalreactions involving intense heat occur, which break down the biomassfeedstock into a gaseous mixture of chemical compounds, i.e., syngas.

Biomass feedstock enters the gasification chamber 122 through thechamber inlet port 120. Here, the feedstock is farthest away from thesource of heat but receives enough heat to experience moistureoff-gassing and removal, i.e., drying of the feedstock. Next, thefeedstock descends further to a hotter portion of the gasificationchamber 122, called the “zone of pyrolysis,” wherein the dried feedstockundergoes a thermochemical process in which the physical phase andchemical composition of the feedstock change in the presence of heat.This thermochemical process results in the production of a mixture ofpyrolysis gases and ash.

After undergoing pyrolysis, the resulting gases and ash move into alower zone in the gasification chamber 122 where they are exposed to anextremely intense plane of heat generated by the combustion of feedstockand pyrolysis gases sustained by a gasification agent, e.g., oxygen.This oxygen, or other gasification/oxidation agents, may enter thegasification chamber 122 through the agent inlet port 124, or ports,where it combusts and provides heat throughout the gasification chamber122.

The exposure of pyrolysis gases to the intense plane of heat results inthermochemical cracking of the gases, wherein the gases decompose intosmaller molecules and basic elements, such as carbon, nitrogen, oxygen,and hydrogen. These molecules and elements then pass into a lower zonewithin the gasification chamber 122 where they undergo oxidation andreduction reactions in which excited electrons are exchanged betweenmolecules and atoms to form a mixture of chemical compounds such ashydrogen gas (H2), carbon dioxide (CO2), carbon monoxide (CO), andnitrogen gas (N2). This mixture of hot gases, i.e., the syngas product,exits the gasification chamber/reactor 122 through the syngas outletport 128, while ash falls to the bottom of the chamber to the ashdepository 126.

FIG. 3 depicts the general structure of a steam generator 118, whichproduces water vapor that may be mixed into the syngas output by thegasifier 100. The steam generator 118 boils water to convert it from aliquid phase to a gaseous phase. The steam generator 118 generallycomprises a heating chamber 134, water inlet port 136, steam outlet port130, and heating element 138. The water inlet port 136 allows water toflow into the heating chamber 134 and the steam outlet port 130 allowssteam and/or water vapor to exit the heating chamber 134.

Various types of heating elements 138 may be implemented to provide heatto the heating chamber 134, such as those including, but not limited to,an open flame fed by biomass, natural gas or other fuel, or an electricheating coil. In preferred embodiments, the same type of fuel used forthe gasifier 100 (e.g., biomass) may also be used to produce heat forthe steam generator 118.

And, in preferred embodiments implemented to achieve maximum possibleefficiency of the present invention, residual heat from the gasifier 100may be captured and repurposed to assist in steam generation. An airinlet 153, may be provided to ensure an appropriate supply of air orother oxidizing agent to sustain combustion of the fuel utilized to heatthe heating chamber 134.

In operation, liquid water flows through the water inlet port 136 intothe heating chamber 134, where it receives heat from the heating element138 via radiation and conduction, and then internally through convectionof the liquid water. As heat is transferred through the heating chamber134 from the heating element 138 to the liquid water 132, it warms andreaches the boiling point, i.e., the temperature of vaporization,wherein the liquid water undergoes a phase change and converts intowater vapor 133. Hot water vapor 133 rises inside of the heating chamber134 and flows out of the heating chamber 134 through the steam outletport 130.

In preferred embodiments, the steam generator is designed such that themaximum amount of heat may be obtained from the heating element 138, soas to improve the overall efficiency of the preset invention. This maybe achieved by, but is not limited to, implementation of a two-coildesign (as shown in FIG. 4) in which water travels through the twocoils, 148 and 150, contained within the heating chamber 134, where itis heated to the point of vaporization.

FIG. 4 depicts a steam generator 118 featuring a two-coil design,wherein the standing liquid water 132 depicted in FIG. 3 is replaced bytwo water-filled heating coils, which function to absorb heat radiatedby the heat source 138 and convected inside the heating chamber 134 andto transfer that heat via conduction to the water 132 contained insidethe coils. The coil stabilizers 142 function to secure and center theinner heating coil 150 within the heating chamber 134 and also tomaintain the location of the outer coil close to the peripheral wall ofthe chamber 134 in order to minimize heat loss by the steam generator118 to the ambient environment.

The outer heating coil 148 runs along the outside plane of the heatingchamber 134, and the inner heating coil 150 is placed in the center ofthe heating chamber 134. Both the inner heating coil 150 and outerheating coil 148 (together “heating coils”) are connected to the steamoutlet port 130 to carry steam and/or water vapor away from the steamgenerator 118. A pressure gauge 144 may be connected downstream, influid communication with the steam outlet port 130, thereby enabling auser to determine pressure inside of the heating coils, 150 and 148. Thewater inlet port 136 and fluid conduit 117 supply liquid water to theinner and outer heating coils, 150 and 148 respectively, located withinthe heating chamber 134.

FIG. 4 further depicts pressure relief valves 145 and 151, pressuremeter 144, steam shut-off valve 146 and water vapor connector port 147,which together function to enable water vapor to flow from the steamgenerator 118 into fluid conduit 119. These aforementioned componentsare designed to ensure that the system will not experience a potentialcatastrophic build-up of pressure that could cause the steam generator118 or its components to rupture or explode.

The pressure relief valves 145 and 151 are placed downstream of theheating coils, wherein pressure relief valve 151 is placed immediatelydownstream of the steam outlet port 130 and pressure relief valve 145 isdownstream of pressure relief valve 151. Pressure relief valve 151 isconfigured to receive a flow of steam from the heating coils and outputthat steam to pressure relief valve 145 or to waste steam outlet pipe152.

Pressure relief valve 145 is configured to receive a flow of steam frompressure relief valve 151 and output a flow of steam to waste steamoutlet pipe 140 or to fluid conduit 119. Waste steam outlet pipes 140and 152 function to carry steam from the steam generator 118 away fromthe steam generator, and deposit that steam into a medium including, butnot limited to, the surrounding environment.

Pressure meter 144, downstream of pressure relief valve 145, functionsto provide to a user a pressure reading of the steam and/or water vaporas it departs the steam generator 118 and travels into fluid conduit119. Steam shut off valve 146 enables a user to shut off the flow ofsteam into fluid conduit 119. Water vapor connector port 147 functionsto provide fluid communication between the steam shut-off valve 146 andthe fluid conduit 119.

In operation, as steam and/or water vapor leaves the heating chamber 134and the inner and outer heating coils, 150 and 148 respectively, watervapor passes through pressure relief valves, 151 and 145, through thepressure meter 144 and the steam shut off valve 146, through the watervapor connector port 147 and into fluid conduit 119, before entering andbeing mixed with the syngas from the gasifier in fluid conduit 102.Water vapor may be released into the environment by pressure reliefvalves, 145 and 151, if the pressure in the steam generator 118 exceedsa safe pressure limit.

Water vapor that is exhausted into the environment may be directedthrough pressure relief valve 151 to exit the steam generator via wastesteam outlet pipe 152 or through pressure relief valve 145 to exit viawaste steam outlet pipe 140. However, if the water vapor pressureremains below the safe limit, the safety valves remain closed and thewater vapor flows through the pressure meter 144 and steam shut offvalve 146, through the water vapor connector port 147 and into fluidconduit 119.

FIG. 5 depicts the two-coil design for a steam generator 118 inoperation. Liquid water flows into the steam generator 118 through thefluid conduit 117 and water inlet port 136 (not depicted in FIG. 5) andpasses into the heating coils, 150 and 148, located inside of theheating chamber 134. Water travels through the heating coils andreceives heat from the heating coils, this heat being transferred by andreceived from the heating element 138, i.e., an open flame, viaconduction, radiation, and/or convection of the air inside of theheating chamber 134.

As the liquid water continues to travel through the heating coils itreaches the point of vaporization, boils and transforms into gaseouswater vapor. This water vapor then passes through the remainder of theheating coils and into the steam outlet port 130 (not depicted in FIG.5).

FIG. 6 depicts the water gas shift reactor 104, which comprises the WGSreaction chamber 156, WGS inlet port 155, catalyst platform 156,catalyst 157, and gas outlet port 158. The catalyst 157 contained insideof the WGS reaction chamber 156 facilitates a chemical reaction in whichwater vapor from the steam generator 118 that is mixed with the syngasproduct reacts with carbon monoxide in the syngas-water vapor mixture toform carbon dioxide and hydrogen gas.

As a result of the WGS reaction, the amount of carbon monoxide includedin the syngas-water vapor mixture is reduced while the amount ofhydrogen gas in the syngas-water vapor mixture is increased.Consequently, this reaction serves a dual purpose of both increasing theamount of the desired end product, i.e., hydrogen, while reducing theamount of toxic carbon monoxide that may poison a hydrogen fuel cell.

As shown in FIG. 6, the catalyst platform 156 functions as a mesh,grating or other porous surface that supports the catalyst while alsopermitting the flow of syngas-water vapor mixture through the WGSreaction chamber 156. The catalyst 157 facilitates the WGS reaction justdescribed by lowering the amount of “energy of activation” required forthis reaction to occur, thereby allowing a greater proportion of thereactant species, i.e., carbon dioxide and water vapor, to acquiresufficient energy of activation to undergo this reaction.

The typical composition of commercial low-temperature shift (LTS)catalysts is generally 32-33% CuO, 34-53% ZnO, and 15-33% Al2O3. Theactive catalytic species is CuO, with the function of ZnO being toprovide structural support and prevent poisoning of the copper bysulfur. The Al2O3 prevents dispersion and pellet shrinkage.

LTS shift reactors typically operate in the range of 200° C. to 250° C.Low reaction temperatures must be maintained due to the susceptibilityof copper to thermal sintering. These lower temperatures also reduce theoccurrence of side reactions that are observed in the case of the HTS.Noble metals such as Pt supported on ceria have also been extensivelyused for LTS.

The typical composition of commercial high-temperature shift (HTS)catalysts is generally 74.2% Fe2O3, 10.0% Cr2O3, and 0.2% MgO (withvolatile components comprising the remaining unaccounted-forpercentage). The chromium acts to stabilize the iron oxide and preventssintering.

HTS catalysts typically operate within the temperature range of 310° C.to 450° C., with temperature increasing along the length of the reactordue to the exothermic nature of the reaction. As such, inlettemperatures are typically maintained at 350° C. to prevent exittemperatures from exceeding 550° C. Industrial reactors generallyoperate at a range from atmospheric pressure to 8375 kPa.

In preferred embodiments the favored LTS catalyst comprising copperoxide-zinc oxide-alumina CuO/ZnO/Al2O3 is used. In addition, thepreferred ratio of water vapor to syngas in the syngas-water vapormixture is 5:1, water vapor to syngas. This ratio enables the maximumefficiency of the present invention.

In operation, the syngas-water vapor mixture enters the WGS reactionchamber 156 through the WGS inlet port 155. Once inside the WGS reactionchamber 156, the syngas-water vapor mixture passes through the catalystplatform 156 and comes into contact with the catalyst 157.

Upon contact, the chemical reaction just described occurs inside of theWGS reaction chamber 156, wherein water vapor in the syngas-water vapormixture is split into hydrogen gas and oxygen, the oxygen bonding withany carbon monoxide present to form carbon dioxide. After the chemicalreaction occurs, resulting gas mixture flows out of the WGS reactionchamber 156 through the gas outlet port 158.

Most of the water vapor exiting the WGS 104 will cooled and condensed bythe heat-exchange two-phase separator 105 and then recycled back to thesteam generator. Liquid water condensed by the two-phase separator 105may be directed through fluid conduit 117 (FIG. 1) to the water inletport 136 of the steam generator 118 for recycling in the steam generator118 and reconversion into water vapor to be mixed with syngas in fluidconduit 102. The gaseous fraction of the fluid processed by theheat-exchange two-phase separator 105 is sent through fluid conduit 115to the scrubber 106.

The scrubber 106 is included in the present invention to facilitateremoval of carbon monoxide from the gas mixture before hydrogen gas isseparated from the gas mixture and, as depicted in FIG. 7, a preferredembodiment of the present invention may include a scrubber 106 thatcomprises a bubbling scrubber, where the gas mixture passes through achemical solution that removes carbon monoxide that remains in the gasmixture following the water-gas-shift reaction in the WGS reactor 104.

And, as depicted in FIG. 7, in preferred embodiments the scrubber 106may comprise a bubbling scrubber. Specifically, the bubbling scrubber106 may employ methanol or a similar liquid as the working fluid.

As shown in FIG. 7 the bubbling scrubber 106 may include, but is notlimited to, a gas mixture inlet pipe 164, bubbling chamber 160, ascrubbing solution and/or suspension 167, bubbler stopper 162, andscrubbed gas outlet pipe 166. The bubbling chamber 160 houses thescrubbing solution 167, and further comprises an air-tight seal createdby the bubbler stopper 162 to ensure that gas mixture does not escapethe bubbling chamber 160 other than through the scrubbed gas outlet pipe166.

The gas mixture inlet pipe 164 is configured to carry gas mixturereceived from fluid conduit 115 to the bottom of the bubbling chamber160, such that gas mixture may exit the gas mixture inlet pipe 164directly into the scrubbing solution and/or suspension 167. The scrubbedgas outlet pipe 166 is configured such that it receives only gas mixturethat has passed through the scrubbing solution and/or suspension 167,and functions to permit gas mixture that has passed through thescrubbing solution and/or suspension 167 to exit the bubbling chamber160. The scrubbed gas outlet pipe 166 connects to fluid conduit 114through which gas mixture may travel to the hydrogen separator 108.

In preferred embodiments, the scrubbing solution and/or suspension 167comprising copper (I) chloride suspended in methanol. In these preferredembodiments, as syngas passes through the methanol-based copper (I)chloride suspension carbon monoxide present in the gas mixture isremoved from the gas mixture and attaches to the copper (I) chloride,forming a metal complex having the chemical formula CuCl(CO).

FIG. 8 depicts a sample configuration of the bubbling scrubber 106 inwhich a standard laboratory beaker is implemented to provide thestructure and bubbling chamber 160 for the bubbling scrubber 106. Thebeaker is filled with the scrubbing solution and/or suspension 167 andthe bubbler stopper 162 is affixed in position at the top of the beakerto provide an air-tight seal.

The gas mixture inlet pipe 164 passes through the bubbler stopper 162and extends into the scrubbing solution and/or suspension 167 at thebottom of the bubbling chamber 160. The scrubbed gas outlet pipe 166passes through the bubbler stopper 162 and extends only into the headportion of the bubbling chamber 160, i.e., the part of the chamber notfilled with scrubbing solution and/or suspension, so as to only receivea scrubbed gas mixture that has passed through the scrubbing solutionand/or suspension167.

In operation, gas mixture from fluid conduit 115 flows into the bubblingscrubber 106 through gas mixture inlet pipe 164, and is carried to thebottom of the bubbling chamber 160 where it bubbles into the scrubbingfluid, a methanol suspension of copper (I) chloride (i.e., CuClsuspended in methanol). The gas mixture forms pockets of gas 168, i.e.,bubbles, in the methanol suspension of copper (I) chloride, that risefrom the bottom of the scrubbing fluid 167 to the top of the scrubbingsolution and/or suspension 167 and into the head portion of bubblingchamber 160.

As the bubbles pass through the scrubbing solution and/or suspension167, carbon monoxide present in the gas mixture remains behind in thescrubbing solution and/or suspension 167, thereby decreasing the amountof carbon monoxide present in the gas mixture exiting the bubblingscrubber 106. The gas mixture exits the bubbling chamber 160 throughscrubbed gas outlet pipe 166 and is carried away from the bubblingscrubber 106 by fluid conduit 114.

The hydrogen separator 108 functions to isolate and separate hydrogengas from the remaining gases in the gas mixture received from thebubbling scrubber 106. The hydrogen separator 108 receives an input ofgas mixture from the bubbling scrubber 106 and outputs two independentstreams of fluid through fluid conduits 112 and 110, wherein fluidconduit 112 contains hydrogen gas and fluid conduit 110 contains amixture of the remaining gases of the gas mixture, including carbondioxide and nitrogen. Hydrogen gas separation may be achieved bymechanisms including, but is not limited to, an electrochemicalseparator, a pressure swing absorption device, or a palladium, platinumor other transition metal-catalyst based membrane purification system.

FIG. 9 depicts a schematic of an electrochemical separator, which isimplemented in preferred embodiments as a hydrogen separator 108 in aneffort to reduce costs of making the present invention while alsoachieving maximum hydrogen separation. The electrochemical separatorcomprises a scrubbed gas inlet port 170, said port receiving a flow ofgas mixture from fluid conduit 114, electrochemical separator gas inputflow channel 172, an anode 176, an electrolyte 178, a cathode 180,external circuit 182, a hydrogen gas outlet port 184, which outputs aflow of hydrogen gas to fluid conduit 112, and a waste gas outlet port174, which outputs a flow of mixed waste gases to fluid conduit 110.

In operation, gas mixture flows through the scrubbed gas inlet port 170into the electrochemical separator gas input flow channel 172. In theelectrochemical separator gas input flow channel 172, hydrogen moleculescontained in the gas mixture separate from the gas mixture and come intocontact with the anode 176, while remaining nitrogen and carbon dioxidegases in the gas mixture flow to and out of the waste gas outlet port174.

Upon contact with the anode 176, hydrogen molecules dissociate intoprotons and electrons. These protons conduct from the anode 176 throughthe electrolyte 178 to the cathode 180; simultaneously, the freeelectrons pass from the anode across the external circuit 182 and aredeposited at the cathode 180.

Upon reaching the cathode 180 side of the electrolyte 178, protons andelectrons bond to form hydrogen atoms and hydrogen atoms bond to form H2gas. This hydrogen gas then exits the electrochemical separator throughthe hydrogen gas outlet port 184 into fluid conduit 112. In preferredembodiments, the electrolyte 178 may comprise a bipolar separator plate,such as a polymer electrolyte membrane.

The elements of the present invention just described together functionto produce ultra-pure hydrogen gas that may be used in a variety ofapplications, including, but no limited to, in a hydrogen fuel cell thatgenerates electricity or in an internal combustion engine. Hydrogen isfirst present in the syngas produced by the gasifier, and the latterelements of the present invention function to increase the amount ofhydrogen gas present in the fluid passing through the present inventionwhile decreasing and effectively eliminating carbon monoxide content.

As a result, hydrogen may be removed from the syngas in the presentinvention as early as directly after the gasifier 100, before reachingother elements. However, as the purpose of the present invention is toproduce ultra-pure hydrogen gas that is free of other chemical elementsand molecules, the purest hydrogen gas will be found after passingthrough the hydrogen separator 108.

In one embodiment for application with a hydrogen fuel cell, hydrogengas departing the hydrogen separator 108 travels through fluid conduit112 into a fuel cell that produces electricity, which fuel cell maycomprise, but is not limited to, a proton exchange membrane (“PEM”) fuelcell, phosphoric acid fuel cell (“PAFC”), solid oxide fuel cell(“SOFC”), hydrogen-oxygen fuel cell, or molten carbonate fuel cell(“MCFC”).

FIG. 10 depicts a schematic of a PEM fuel cell 190, which functions togenerate electricity by passing the electron of a hydrogen atom acrossexternal circuit 200. The PEM fuel cell 190 comprises an anode 194, aporous proton exchange membrane 196, a cathode 198, as well as anexternal circuit 200, hydrogen gas inlet port 192, air inlet port 202,and water outlet port 204. Electricity may be drawn from the externalcircuit 200 that acts as a bridge around the proton exchange membrane196 for electrons.

In operation, hydrogen gas enters the PEM fuel cell 196 from fluidconduit 112, through the hydrogen gas inlet port 192 and comes intocontact with the anode 194, where hydrogen atoms dissociate into protonsand electrons. Following dissociation, protons are conducted through theproton exchange membrane 196 from the anode 194 to the cathode 198 whileelectrons are forced to pass the proton exchange membrane 196 in thesame direction as the protons via the external circuit 200.

After reaching the cathode 198 side of the proton exchange membrane 196,protons and electrons interact with oxygen that has entered the PEM fuelcell 196 through the air inlet port 202 to form water. Water then exitsthe PEM fuel cell 196 through the water outlet port 204.

In the embodiments for application in a hydrogen fuel cell, liquid waterexiting the water outlet port 204 of the PEM fuel cell 196 may berecycled, wherein it is redirected through a fluid conduit to the waterinlet port 136 of the steam generator 118 and converted to water vaporthat is later mixed with syngas in fluid conduit 102.

This design will serve to improve the overall efficiency of the system,allowing for more efficient use of the byproducts of the biomass.However, it should be understood that claimed subject matter need notredirect water through a fluid conduit to the steam generator, but maynot use the water produced by the PEM fuel cell 196 whatsoever, or mayuse the water for other purposes.

While the embodiments just described generally include the use of abubbling solution and/or suspension scrubber, it should be understoodthat claimed subject matter is not intended to be limited in scope tothe particular design of the scrubber that is disclosed. But instead,the invention may integrate other forms of scrubbers such as a palladiumor platinum membrane scrubber. Such scrubbers may or may not requirestoppers and/or seals to maintain an airtight scrubber environment, mayinclude more than one seal, and may rather include any scrubber designthat results in the gas mixture received from the WGS being sufficientlyscrubbed of unwanted carbon monoxide.

It should further be understood that, although several specificembodiments have just been described, claimed subject matter is notintended to be limited in scope to any particular embodiment orimplementation. In the preceding description, various aspects of claimedsubject matter may have been described. For purposes of explanation,specific numbers, systems, or configurations may have been set forth toprovide a thorough understanding of claimed subject matter.

However, it should be apparent to one skilled in the art having thebenefit of this disclosure that claimed subject matter may be practicedwithout those specific details. In other instances, features that wouldbe understood by one of ordinary skill were omitted or simplified so asnot to obscure claimed subject matter. While certain features have beenillustrated or described herein, many modifications, substitutions,changes, or equivalents may not occur to those skilled in the art. Itis, therefore, to be understood that the appended claims are intended tocover all such modifications or changes as fall within the true spiritof the claimed subject matter.

What is claimed is:
 1. An ultra-pure hydrogen synthesis system whichcomprises: a gasifier; an oils and tars filtration system; a steamgenerator; a water gas shift reactor, containing a catalyst thatfacilitates one or more chemical reactions between carbon monoxide andwater; a heat-exchange two-phase water condenser and separator; ascrubber; a hydrogen separator; one or more fluid conduits, wherein thefluid conduits connect to and establish fluid communication between eachof the gasifier, the oils and tars filtration system, the steamgenerator, the water gas shift reactor, the scrubber and the hydrogenseparator.
 2. The ultra-pure hydrogen synthesis system of claim 1,wherein the gasifier is a down draft gasifier.
 3. The ultra-purehydrogen synthesis system of claim 1, wherein catalyst of the water gasshift reactor comprises copper, zinc, and aluminum oxides.
 4. Theultra-pure hydrogen synthesis system of claim 1, further comprising ahydrogen fuel cell.
 5. The ultra-pure hydrogen synthesis system of claim1 wherein the hydrogen separator is an electrochemical separator.
 6. Theultra-pure hydrogen synthesis system of claim 1, wherein the hydrogenseparator is a swing absorption system.
 7. The ultra-pure hydrogensynthesis system of claim 1, wherein the hydrogen separator is apalladium, platinum or other transition metal-catalyst based membranehydrogen purification system.
 8. The ultra-pure hydrogen synthesissystem of claim 1, wherein the scrubber is a liquid-based bubblingscrubber.
 9. The ultra-pure hydrogen synthesis system of claim 8,wherein the liquid contained within the scrubber is an aqueous solutionof copper chloride and methanol.
 10. The ultra-pure hydrogen synthesissystem of claim 1, wherein the oils and tars filtration system is anactivated carbon filter.
 11. A method of producing ultra-pure hydrogenfrom biomass, comprising the steps of: feeding a biomass feedstock intoa gasifier and using the gasifier to perform gasification and pyrolysisof the biomass feedstock, which converts into a syngas product thatincludes molecules of nitrogen, carbon dioxide, carbon monoxide, andhydrogen; outputting the syngas product from the gasifier into an oilsand tars filtration system; filtering any oils and tars from the syngasproduct using an oils and tars filtration system; outputting thefiltered syngas product from the oils and tars filtration system;producing steam and water vapor using a steam generator; mixing thefiltered syngas product with steam or water vapor produced by the steamgenerator to create a syngas-water vapor mixture; feeding thesyngas-water vapor mixture into a water gas shift reactor and using thewater gas shift reactor to modify the syngas product by increasing theamount of hydrogen gas and decreasing the amount of carbon monoxide,wherein the water gas shift reactor contains a catalyst that facilitatesa chemical reaction between carbon monoxide and water to convert thesyngas-water vapor mixture into a gas mixture that includes molecules ofhydrogen, and other byproduct gases including nitrogen, carbon dioxide,dihydrogen monoxide (water vapor), and trace amounts of carbon monoxide;outputting the gas mixture from the water gas shift reactor; feeding thegas mixture output from the water gas shift reactor into a scrubber andusing the scrubber to remove the remaining trace amounts of carbonmonoxide from the gas mixture; outputting scrubbed gas from thescrubber; feeding the gas mixture output from the scrubber into ahydrogen separator and using the hydrogen separator to isolate hydrogengas molecules from the remaining byproduct gases and create ultra-purehydrogen gas; and outputting ultra-pure hydrogen gas from the hydrogenseparator.
 12. The method of producing ultra-pure hydrogen from biomassof claim 11, wherein the gasifier is a down draft gasifier.
 13. Themethod of producing ultra-pure hydrogen from biomass of claim 11,wherein the catalyst of the water gas shift reactor comprises copper,zinc, and aluminum oxides.
 14. The method of producing ultra-purehydrogen from biomass of claim 11, wherein the ultra-pure hydrogen isoutput from the hydrogen separator into a hydrogen fuel cell.
 15. Themethod of producing ultra-pure hydrogen from biomass of claim 11 whereinthe hydrogen separator is an electrochemical separator.
 16. The methodof producing ultra-pure hydrogen from biomass of claim 11, wherein thehydrogen separator is a swing absorption system.
 17. The method ofproducing ultra-pure hydrogen from biomass of claim 11, wherein thehydrogen separator is a palladium, platinum or other transitionmetal-catalyst based membrane hydrogen purification system.
 18. Themethod of producing ultra-pure hydrogen from biomass of claim 11,wherein the scrubber is a liquid-based bubbling scrubber.
 19. The methodof producing ultra-pure hydrogen from biomass of claim 18, wherein theliquid contained within the scrubber is an aqueous solution of copperchloride and methanol.
 20. The method of producing ultra-pure hydrogenfrom biomass of claim 11, wherein the oils and tars filtration system isan activated carbon filter.